474 METABOLISM, NUTRITION, AND DIET 



the tendency to decomposition which belongs to badly nourished tissues; 

 and death occurs often with symptoms of nervous disorder, delirium, or 

 convulsions. Death commonly occurs within from six to ten days after 

 total deprivation of food. This period may be considerably prolonged by 

 taking a very small quantity of food, or even by water alone. The cases 

 so frequently related of survival after many days or even some weeks of 

 abstinence have been due either to the last- mentioned circumstances, or to 

 other no less effectual conditions which prevented the loss of heat and 

 moisture. 



During the starvation period the excretions diminish. The urea, as rep- 

 resenting the nitrogen, falls quickly in amount, reaches a minimum where it 

 remains fairly constant for several days before death. The sulphates and 

 phosphates undergo much the same type of reduction. The carbon dioxide 

 given out and the oxygen taken in diminish. The feces diminish as well as 

 the bile. It is highly probable that the greater part of the nitrogen represents 

 the loss of weight of the muscles. 



In starvation, then, we see that the only income consists of water and 

 the inspired oxygen. The whole of the energy of the body given out in the 

 form of heat and mechanical labor is obtained at the expense of its own 

 tissues, there being as a result a constant drain of the nitrogen and carbon, 

 not to mention the other elements of which the tissues are composed. It is 

 obvious that such a condition cannot be endured for any length of time. 



REQUISITES OF A NORMAL DIET. 



For many years the dictum has been accepted that it is only necessary 

 that a normal diet should be made of the various classes of food in suffi- 

 cient quantity to supply to the normal adult animal body the amount of 

 energy that is lost, due to the daily round of activity. In addition, in 

 young and growing animals an excess of the classes of foods used in the 

 construction of new tissue must also be given. No doubt these desid- 

 erata may be satisfied by many combinations of foods, and it would be un- 

 reasonable to expect the diet of every adult to be the same. The age, sex, 

 strength, and circumstances surrounding each individual must ultimately 

 determine what he takes as food. A dinner of bread and cheese with an 

 onion contains all the requisites for a meal, but such diet would be suitable 

 only for those possessing strong digestive powers. It is a well-known fact 

 that the diet of the continental nations differs from that of our own coun- 

 try, and the diet of dwellers in cold from that of those who live in hot 

 climates, but the same principle underlies all, viz., the replacement of the 

 energy losses of the body in the most convenient and economical way 

 possible. Any one in active work requires more food than one at rest, and 

 growing children require more food in proportion to body weight than adult 

 men and women, but of a different variety. 



